A particle measuring apparatus using an optical flow cytometer is conventionally known. In this type of particle measuring apparatus, a specimen containing testing particles such as blood, and the like, is flowed through a flow cell, and the flow path is irradiated with the light emitted from a light source. The light emitted from each particle is detected by a light receiving optical system, and the particles are classified and counted based on the detected light.
US Patent Application Publication No. 2009/122311A describes a particle measuring apparatus that irradiates a specimen containing stained cells with a plurality of laser lights having different wavelengths, and acquires fluorescence excited and generated from the respective laser lights.
However, in the particle measuring apparatus of US Patent Application Publication No. 2009/122311A, a band pass filter that selectively transmits the blue laser beam is used in a forward scattered light detection device, and a band pass filter BPF1 that transmits only the blue side scattered light is also used with respect to a photomultiplier tube PMT1 for detecting the side scattered light. Thus, only the scattered light generated when the blue laser beam is scattered by cells is used for the scattered light when analyzing the particles.